I purchased these Friday and went on a short ride Sunday with them. I don't feel much of a notable power difference from the stock carnivores with these on which is a huge positive. Went up into some rocks for most of the day and then into the mud a little as well. I'm not a huge mud guy but we've had a good amount of rain in the last couple weeks so it was there. Tires did good in that as well, actually better than I expected. Im also not through the break in period yet on my 21 trail so I didn't do anything real wild. The machine still has about 27 miles on it now after putting 10 or so on it Sunday. Sidewalls are little stiff and tall so I may experiment running as low as 4 or 5 psi in them, at 10 psi they had little to no sidewall flex still. Overall I'm real happy with the tires performance so far.